In the wake of this winter flu season, the holding of mass gathering, such as Kumbh Mela, may pose health risks. Maha Kumbh has been a case of study among health experts for a long time. Here’s what studies and research have to say about health challenges at Maha Kumbh.

While the Kumbh Mela festival is ordinarly held every three years, rotating between several holy cities on the banks of these rivers, the Maha Kumbh Mela occurs only once every 12 years. Maha means “great”, and the event attracts the most devotees because it is considered the most auspicious and holy in the cycle.

Hindu devotees from across India flocked to the northern city of Prayagraj yesterday as the world's largest religious festival began. Over the coming 45 days, an estimated 400 million Hindus are expected to come together for Maha Kumbh Mela.

The Hindu festival of Kumbh Mela, considered the largest human gathering on the planet, began in northern India on Monday with thousands of pilgrims flocking to the holy confluence of the Ganges, Yamuna and Sarasvati rivers.

Vast crowds of Hindu pilgrims in India bathed in sacred waters as the Kumbh Mela festival opened on Monday, with organisers expecting 400 million people -- the world's largest gathering

Hindu devotees gather for festival in India Live from Prayagraj as millions of Hindu devotees gather in the north Indian state of Uttar Pradesh for the Maha Kumbh festival, said to be the largest religious congregation on Earth.